Soft multifocal contact lens

ABSTRACT

A multifocal contact lens ( 10, 50 ) made of flexible material is able to translocate on an eye by virtue of a lower end ( 22 ) of the contact lens ( 10, 50 ) being truncated so as to provide a relatively wide surface. The lower end ( 22 ) engages with the lower eyelid of a wearer. The lower end ( 22 ) may be provided with a forwardly projecting ledge ( 52 ).

CROSS REFERENCE TO RELATED APPLICATION

The present application claims benefit of earlier filed patentapplications. This application is a continuation of U.S. applicationSer. No. 11/442,694, filed May 26, 2006, entitled “SOFT MULTIFOCALCONTACT LENS” which is a continuation of U.S. application Ser. No.10/836,457 filed Apr. 30, 2004, entitled “SOFT MULTIFOCAL CONTACT LENS”which is a continuation-in-part of U.S. application Ser. No. 10/149,871,filed on Jun. 13, 2002, entitled “SOFT MULTIFOCAL CONTACT LENS,” whichis a 35 U.S.C. §371 filing of International Patent Application No.PCT/AU00/01531, filed on Dec. 13, 2000, and entitled “SOFT MULTIFOCALCONTACT LENS.” which further claims priority benefit of AustralianPatent Application No. PQ4683 filed on Dec. 16, 1999, and entitled “SOFTMULTIFOCAL CONTACT LENS.” The entire content of all these relatedapplications are hereby incorporated by reference in their entirety asfor all purposes.

BACKGROUND Field of the Invention

The present invention relates to multifocal contact lens.

SUMMARY OF THE INVENTION

In accordance with one aspect of the present invention there is provideda multifocal contact lens made of flexible material and adapted totranslocate on an eye. In one example, the contact lens includes adistant vision segment and a close range vision segment; the lens havinga periphery, a front surface, a rear surface having a curvature, anupper end, and a lower end. The distant vision segment is located closeto the upper end relative to the close range vision segment which islocated close to the lower end. A truncated portion is located at thelower end, the truncated portion being arranged to rest on a lowereyelid, and a forwardly projecting ledge is positioned at the lower endof the contact lens. The forwardly projected ledge is configured so asto project forward of a line formed by a downward extension of thecurvature of an adjacent portion of the front surface. In one example,the forwardly projected ledge includes a ridge or raised strip at thelower end of the lens.

In another example, the contact lens includes a distant vision segmentand a close range vision segment; the lens having a periphery, a frontsurface, a rear surface having a curvature, an upper end, and a lowerend. The distant vision segment is located close to the upper endrelative to the close range vision segment which is located close to thelower end. A truncated portion is located at the lower end, thetruncated portion being arranged to rest on a lower eyelid. The distantvision segment and the close range vision segment meet along asubstantially straight line. In one example, the line is parallel to thetruncated portion when viewed from the front surface. The lens mayfurther include a forwardly projecting ledge at the lower end of thecontact lens.

In another example, the contact lens includes a distant vision segmentand a close range vision segment; the lens having a periphery, a frontsurface, a rear surface having a curvature, an upper end, and a lowerend. The distant vision segment is located close to the upper endrelative to the close range vision segment which is located close to thelower end. A truncated portion is located at the lower end, thetruncated portion being arranged to rest on a lower eyelid. The lensfurther including at least one secondary curve portion located at therear surface adjacent the periphery, the at least one secondary curveportion having a curvature which is less pronounced than that of therear surface. The secondary curve portion aids smooth translocation on apatient's eye. Additionally, the lens may further include a forwardlyprojecting ledge at the lower end of the contact lens.

In another example, the contact lens includes a distant vision segmentand a close range vision segment; the lens having a periphery, a frontsurface, a rear surface having a curvature, an upper end, and a lowerend. The distant vision segment is located close to the upper endrelative to the close range vision segment which is located close to thelower end. A truncated portion is located at the lower end, thetruncated portion being arranged to rest on a lower eyelid, and aforwardly projecting ledge is located at the lower end of the contactlens. The forwardly projecting ledge having a lower surface which isalso arranged to rest on the lower eyelid of the user.

The present invention and its various embodiments are better understoodupon consideration of the detailed description below in conjunction withthe accompanying drawings and claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will now be described, by way of example, withreference to the accompanying drawings, in which:

FIG. 1 is a front perspective view of a contact lens in accordance witha first embodiment of the present invention;

FIG. 2 is a cross-section along the line A-A of FIG. 1;

FIG. 3 is a front perspective view of a contact lens in accordance witha second embodiment of the present invention;

FIG. 4 is a cross-section along the line B-B of FIG. 3;

FIGS. 5A-5C illustrate cross-sectional views of exemplary contact lenshaving secondary curve portions; and

FIGS. 6A-6C illustrate cross-sectional views of exemplary contact lenshaving secondary curve portions.

DETAILED DESCRIPTION OF THE INVENTION

In FIGS. 1 and 2 of the drawings there is shown a contact lens 10 havinga front surface 12 and a rear surface 14.

As shown in the drawings, the front surface 12 is subdivided into adistant vision front segment 16 and a close range vision front segment18.

A distant vision front segment 16 has a curvature which preferablyconforms to a spherical, aspherical or toroidal shape. It has been foundthat use of an aspherical shape for the front segment 16 enables thelens 10 to be made relatively thin.

Similarly, the close range vision front segment 18 has a curvature whichpreferably conforms to a spherical, aspherical or toroidal shape. It hasbeen found that the use of an aspherical shape allows for aprogressively variable close range reading area.

The segments 16 and 18 may meet along a laterally expanding line 20 asshown in FIG. 1 depending on the respective curvatures of the segments16 and 18. Alternatively, the segments 16 and 18 may meet at a point.

The segment 18, as can be seen in FIG. 2, may be relatively thickcompared to the segment 16 and may be in the form of a prism.

The prism stabilizes the contact lens 10 on the eye and the amount ofthe prism depends on the lens power but it is preferably sufficient tohold the lens in position on the eye without rotation and without beinguncomfortable for the patient.

The contact lens 10 is formed of a flexible material which is also soft.For example the contact lens 10 may be formed of soft hydrogel, siliconeor a hybrid material formed from soft hydrogel and silicone or otherflexible, non-rigid material. Further, the lens 10 is relatively largebeing, for example, larger than a corneal lens.

The contact lens 10 has a lower end 22 and an upper end 24. The prism islocated adjacent the lower end 22. The presence of the prism adjacentthe lower end 22 results in the contact lens 10 having a relativelybulky and heavy portion adjacent to the end 22. The end 22 is, as canbest be seen in FIG. 2, truncated so as to leave an end surface which isrelatively deep as shown in FIG. 2, compared to a nontruncated end. Thetruncation of the end 22 allows the contact lens 10 to rest on a lowereye lid of a patient so as to engage and hold the contact lens 10 inposition.

Further, the rear surface 14 of the lens 10 is formed in a curved shapewhich may be spherical or aspherical or may be toroidal to correct for apatient's astigmatism. Further, adjacent the end 22 and the end 24 therear surface 14 is preferably formed with secondary curve portions 26 or28 respectively. The secondary curve portions 26 and 28 have a curvaturewhich is less pronounced than that of the rear surface 14 so as tomodify the lens fitting on the eye so as to facilitate translocation.The secondary curves may each be a single curve, a series of curves, anaspherical curve, or a combination of these curves.

The secondary curve portions 26 and 28 are less pronounced (i.e.,flatter) than the curvature of the main rear surface 14 of lens 10. Invarious examples, the secondary curve portions 26 and 28 may include oneor more of flatter curves, varying widths, varying curves, a series ofblended flatter curves, aspheric, or some other design that graduallymakes the peripheral secondary curve portions 26 and 28 of lessercurvature (flatter) than the curvature of rear surface 14. The flatterperipheral curve enables lens 10 to more readily move (translate) overthe flatter scleral portion of the eye when the eye looks down and thelens translates on the eye as described below.

In one example, a translating bifocal lens is provided with a peripheralcurvature of sufficient flatness and width to allow for the lens toeasily move (i.e., translate) up when the patient looks down and thelower eyelid engages the lower portion of the lens. An exemplary softlens is shown in FIGS. 5A and 5B, and includes a peripheral curveportion 28 a that is approximately 0.5 mm wide and 1.00 mm flatter inradius than the base curvature of rear surface 14 of the lens. FIGS. 6Aand 6B illustrate another exemplary lens including a curve portion 28 bhaving a peripheral curvature that is preferably flatter than thecurvature of rear surface 14 in the range from 0.75 mm and 3.00 mm, andmore preferably between 1.0 mm and 2.75 mm. The width of the peripheralcurved portion 28 a is preferably in a range from 0.5 mm to 5.0 mm, morepreferably 0.75 mm to 4.0 mm, and yet more preferably 1.1 mm to 2.50 mm.As illustrated in FIG. 6B, the sclera (the white area of the eye)generally has a curvature that is flatter than the curvature of thecornea. The flatter and wider peripheral curve of the translatingbifocal lens shown in FIGS. 6A and 6B allows the lens to slide ortranslate easily upwards onto the sclera when the user looks down andthe lens engages the ledge 52 as shown in greater detail in FIG. 6C. Incontrast, FIG. 5C illustrates the exemplary lens shown in FIGS. 5A and5B having a less flat and wide peripheral curve (e.g., a curvaturecloser to the curvature of rear surface 14), which makes translationmore difficult as the lens is more likely to dig into the flattercurvature of the sclera.

The secondary curve portions 26 and 28 may only extend along part of theperiphery of the lens 10 adjacent the ends 22 or 24 or they could belengthened to extend around most of or all of the periphery of the lens10.

The position of the junction 20 between the segments 16 and 18 may bevaried as with bifocal spectacle lens, so that the position of the closerange vision portion 18 may be customized to each patient. This allowsthe lens 10 to be fitted precisely to an eye of an individual patient.

As discussed above, the lower portion of the lens 10 adjacent the end 22is bulkier and heavier than the upper portion adjacent the end 24. Thisensures that the lens 10 is orientated in the correct way in use so thatthe distant vision segment 16 is uppermost and the close range visionsegment 18 is lowermost.

Additionally, a lens including an astigmatic or toroidal powercorrection may be incorporated on either the front surface 12 or rearsurface 14 of the lens. A toroidal lens is placed in a specific axis inthe lens, and the bifocal lens incorporating the toroidal power isdesirably located at a precise and stable position on the eye so thecorrective prescription is maintained at the desired position. Thetruncated end 22 (and/or forwardly projecting ledge 52 described below)is designed to position the lens, resting on the lower lid, such thatthe lens is in a proper position on the eye during use to enable thecorrective power more effectively.

Further, the contact lens 10 may have lateral lenticular portions 30adjacent sides thereof. The lenticular portions 30, where present, arecut away portions which reduce lens bulk.

The contact lens 10 preferably has an overall size of from 10 to 16 mmpreferably from 12.5 to 14.5 mm. The truncation at the lower end 22 mayreduce the overall size of the lens by from 0.05 to 5 mm preferably byfrom 0.5 to 3 mm.

The contact lens 10 could have a third intermediate power vision segmentbetween the segments 16 and 18. Further, the close range vision segment18 may include an intermediate segment which is preferably aprogressively variable or graduated portion for close vision.

In use, the lens 10 of FIGS. 1 and 2 is fitted to a patient's eye withthe end 22 resting on the lower eyelid of the patient. Thus, when thepatient looks downward, the eye moves relative to the contact lens 10 sothat the visual axis is through the close, intermediate or graduatedrange vision segment 18.

The contact lens 10 cannot move downward because of the engagementbetween the end 22 and the lower eyelid. Alternatively, when the patientlooks up, the eye moves again relative to the contact lens 10 which isretained in place by the weight of the segment 18, so that the visualaxis is through the upper portion of the contact lens 10 correspondingto the top portion or distant vision segment 16.

Thus, in operation, the contact lens 10 translocates relative to the eyeso that the patient can selectively look through the lower close rangevision segment 18 or the distant vision segment 16. Translocation isaided by the presence of the secondary curve portions 26 and 28.

Line 20, illustrating the straight line demarcation between distancesegments 16 and 18, provides a bifocal lens without (or at leastreduced) undesirable “image jump” when looking from the distant portionof the lens to the close range portion of the lens. In particular, thereis no sudden introduction of a prismatic effect by the close rangeportion at the dividing line, or at least at the point where the eyecrosses the dividing line, in the translation of the eye from thedistant portion to the close range portion of the lens as common inbifocal lenses having curved demarcation lines. Where the demarcationbetween distance and close vision segments is curved, the close visionsegment exerts a prismatic effect at all points within its circumferencerelative to the distance portion of the lens. The effect for a user isthat all objects seen through the close segment appear to have “jumped”to a new position when transitioning between segments. Moreparticularly, with curved bifocals, the position of the optical centersof the distance and the close range portions of the lens is dependant onthe powers of the lens and are always displaced. As the direction ofgaze is lowered, the eye meets a gradually increasing prismatic effectas the line of vision moves away from the distance optical center. Justafter it crosses the dividing line into the close range portion itsuddenly meets the base down effect exerted by the close range segment.The effect on the wearer is that all the objects seen through thesegment appear to have jumped to a new position. An obvious effect ofthe ‘jump’ is the loss in visual field. The magnitude of the jumpdepends, at least in part, on the distance between the optical centersof the distance and the close range portions of the lens, which isdependant on the powers of the distance and the close range portions ofthe lens.

The exemplary configurations described herein, including a straight line20 between segments 16 and 18, may allow a user's clarity of vision,when looking from the distance to the reading portion of the lens, to beclear and with reduced distortion or blurred vision caused by thedifferent segments. In one example, line 20 is a substantially straighthorizontal line along the curvature of the front surface 12, e.g.,parallel to lower end 22, when viewed from the major front surface oflens 10. The optical center of a lens is the only point in the lenswhere there is no prismatic effect. With the straight line bifocaldesign, the optical centers at least closely coincide resulting inelimination of the image jump (or at least reduced image jump relativeto curved demarcation lenses) as the eye moves from the distance portionto the close range portion of the lens. In one example, a bifocal lensincludes a straight line dividing the distance and the close rangeportions of the lens having a virtual superimposition of the opticcenters of both the distance and the close range portions on thedividing line.

In FIGS. 3 and 4, there is shown a contact lens 50 which is similar tothe contact lens 10 and like reference numerals denote like parts.

In this case, however, the lower end 22 is provided with an integralforwardly projecting ledge 52 which, in use, is arranged to rest on thelower eyelid. The use of the ledge 52 has the advantage that the segment18 may be made thinner than in the contact lens 10. Alternatively, theledge 52 may be used in conjunction with a prism to add bulk to thelower part of the contact lens 50 to assist in correct lens orientation.

Further, the use of a thinner segment 18 reduces the overall weight ofthe contact lens 50. Thus, the contact lens 50 may or may not have thelenticular portions 30 of the contact lens 10.

The ledge 52 may extend across the entire lower end 22 of the lens 50 orover only a portion of the lower end 22. Typically, the ledge 52 may befrom 2 to 10 mm, preferably from 4 to 6 mm wide at the end 22 where thecontact lens 50 is truncated.

The presence of the ledge 52 adds bulk to the lower end 22 so allowinggood lid action on the contact lens 50 to allow for lens translocation.

Further, as can be seen in FIG. 3, the ledge 52 may be provided withupwardly curved end portions 54 which act as weights and help tostabilize the contact lens 50 in use. The ledge 52 and the portions 54may be conveniently formed by means of a lather or incorporated in amould depending on the method of manufacture. Modifications andvariations as would be apparent to a skilled addressee are deemed to bewithin the scope of the present invention.

Additionally, in one example, ledge 52 may be configured to projectforward of a line formed by a downward extension of curvature of anadjacent portion of the front surface 12, for example, extending forwardof the curvature of the lower, close range portion 18. The forwardlyprojecting ledge 52 thereby forms a ridge or elevated portion extendingout from the adjacent surface, which is configured to assist in abuttinga patient's eyelid and thereby aid in translocation of the lens on theeye. In one example, ledge 52 includes a raised strip formed along aportion of close range portion 18 and adjacent the lower end 22.

The above detailed description is provided to illustrate exemplaryembodiments and is not intended to be limiting. It will be apparent tothose of ordinary skill in the art that numerous modification andvariations within the scope of the present invention are possible.Further, various combinations of different examples may be used alone orin combination. Additionally, particular examples have been discussedand how these examples are thought to be advantageous or address certaindisadvantages in related art. This discussion is not meant, however, torestrict the various examples to methods and/or systems that actuallyaddress or solve the disadvantages.

1. A multifocal contact lens, comprising a distant vision segment; aclose range vision segment; the lens having a periphery, a frontsurface, a rear surface having a curvature, an upper end, and a lowerend, wherein the distant vision segment and the close range visionsegment meet at least partially along a substantially straight linealong the front surface.
 2. A multifocal contact lens according to claim1, wherein the substantially straight line along the front surface islocated closer to the lower end than the upper end.
 3. A multifocalcontact lens according to claim 1, wherein the substantially straightline along the front surface is located closer to the upper end than thelower end.
 4. A multifocal contact lens according to claim 1, whereinthe substantially straight line along the front surface is centeredbetween the upper end and the lower end.
 5. A multifocal contact lensaccording to claim 1, wherein the distance vision segment and the closerange segment meet in the substantially straight line along the frontsurface such that there is no image jump effect when an eye translatesform the distance vision segment to the close range vision segment.
 6. Amultifocal contact lens according to claim 1, wherein the distancevision segment and the close range segment meet in the substantiallystraight line along the front surface such that there is reduced imagejump effect when an eye translates form the distance vision segment tothe close range vision segment relative to curved demarcation betweenthe distant vision segment and the close range segment.
 7. A multifocalcontact lens according to claim 1, further comprising a forwardlyprojecting ledge disposed close to the lower end, the forwardlyprojected ledge allowing for lower lid contact to enable for thetranslocating of the contact lens on an eye.
 8. A multifocal contactlens according to claim 7, wherein the forwardly projecting ledgeincludes a ridge extending forward of the front surface of the lower endof the contact lens.
 9. A multifocal contact lens according to claim 7,wherein the forwardly projecting ledge includes a raised strip or areaalong the lower end of the contact lens.
 10. A multifocal contact lensaccording to claim 7, further including a truncated portion located atthe lower end, wherein the truncated portion is arranged to rest on alower eyelid and wherein the forwardly projecting ledge is also arrangedto rest on the lower eyelid.
 11. A multifocal contact lens according toclaim 10, wherein the truncated lower end and the forwardly projectingledge have respective end surfaces which are coplanar with one anotherand are substantially straight.
 12. A multifocal contact lens accordingto claim 10, wherein the truncated lower end and the forwardlyprojecting ledge have respective end surfaces angled to engage a lowerlid that is not parallel to an upper lid.
 13. A multifocal contact lensaccording to claim 7, wherein the forwardly projecting ledge extendssubstantially along at least a portion of the lower end of the lens. 14.A multifocal contact lens according to claim 7, wherein the forwardlyprojecting ledge further includes upwardly curved end portions.
 15. Amultifocal contact lens according to claim 1, further including atruncated portion located at the lower end, wherein the truncatedportion is arranged to rest on a lower eyelid.
 16. A multifocal contactlens according to claim 15, wherein the substantially straight linewhere the close range vision segment and distant range vision segmentmeet is parallel to the truncated portion as viewed from the frontsurface.
 17. A multifocal contact lens according to claim 15, whereinthe substantially straight line where the close range vision segment anddistant range vision segment meet are inclined with respect to thetruncated portion as viewed from the front surface.
 18. A multifocalcontact lens according to claim 1, further including at least onesecondary curve portion located at the rear surface adjacent theperiphery, the at least one secondary curve portion having a curvaturewhich is less pronounced than that of the rear surface.
 19. A multifocalcontact lens, comprising a distant range vision segment; a close rangevision segment; and an intermediate range vision segment between theclose range vision segment and the distant range vision segment, theintermediate segment having a power or progressive power between thedistant range vision segment and the close range vision segment, thelens having a periphery, a front surface, a rear surface having acurvature, an upper end, and a lower end.
 20. A multifocal contact lensaccording to claim 19, wherein the distant range vision segment and theintermediate range vision segment meet along a substantially straightline along the front surface.
 21. A multifocal contact lens according toclaim 19, wherein the close vision segment and the intermediate rangevision segment meet along a substantially straight line along the frontsurface.
 22. A multifocal contact lens according to claim 19, whereinthe intermediate range vision segment comprises a progressively variablepower from the power of the distant range vision segment to the closerange vision segment.
 23. A multifocal contact lens according to claim19, wherein the intermediate range vision segment comprises anincreasingly progressively variable power from the power of the distantrange vision segment to the close range vision segment.
 24. A multifocalcontact lens according to claim 19, further comprising a forwardlyprojecting ledge disposed close to or at the lower end, the forwardlyprojected ledge allowing for lower lid contact to enable for thetranslocating of the contact lens on an eye.
 25. A multifocal contactlens according to claim 24, further including a truncated portionlocated at the lower end, wherein the truncated portion is arranged torest on a lower eyelid and wherein the forwardly projecting ledge isalso arranged to rest on the lower eyelid.
 26. A multifocal contact lensaccording to claim 19, further including a truncated portion located atthe lower end, wherein the truncated portion is arranged to rest on alower eyelid.